The aim of this project is to build a new very high spatial resolution, rapid frame rate region of interest (ROI) x-ray detector system, the micro-angiographic fluoroscope (MAF) and to use it for guiding and evaluating new stents used for flow modification in the treatment of intracranial aneurysms. The detector due to its large adjustable gain will be capable of acquiring 30 fps at both fluoroscopic exposures in the fractional microR and higher range as well as at angiographic exposures in the mR range. The detector will have adjustable pixel size and be capable of pixel sizes less than 50 mu/m and will have high-contrast spatial resolution greater than 10 lp/mm while operating at typical angiographic kVp's. The MAF will have a viewing field of at least 5 cm diameter sufficient for viewing small regions where interventions and in particular flow modifying interventions are occurring. The MAF will be compatible with existing commercial angiographic x-ray sources and be mounted in such a way as to be interposed between the x-ray image intensifier, X/I, of the commercial system and the phantom, animal, or patient so that the MAF can be used when its high resolution ROI capabilities are needed, usually at critical times during interventional procedures. Additionally, the MAF will be used for cone-beam rotational microangiography and micro-computed tomography (CT) for determining vessel lumens needed for accurate flow assessment. Also, the new imaging capability for accurate localization will allow the development and implementation of new devices: asymmetric, variable porosity stents for treatment of cerebral aneurysms by modifying aneurysm blood flow characteristics. To optimize the new stent design, flow reduction in aneurysms needed to induce thrombosis will be explored. Also details of flow and flow modification will be investigated using advanced theoretical and experimental methods. Finally clinical application of the high-resolution microfluoroscopic detector will be used to evaluate the use of stents for flow modification in the cerebrovasculature of human patients.